Run benchmarks with the min supported Kotlin version

[qurbonzoda]

The library states the minimum supported Kotlin version in README. However, in integration tests, that Kotlin version is only tested for not reporting warning or error. The benchmarks are actually not run in a project that uses the minimum supported Kotlin. Running some or all tests with that version would guarantee stable support for the stated version.

So the idea is publishing kx-benchmark plugin and runtime with a newer Kotlin and using it in a project that uses an older Kotlin.